Manufacture of lubricating oil



creases in the oxidation stability of the oil.

Patented Dec. 30, 1947 MANUFACTURE OF LUBRICATING OIL Fred C. Toettcher, Fishkill, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application January 19, 1946, Serial No. 642,417

2. Claims.

This invention relates to the treatment of hydrocarbon oils to produce lubricating oil highly resistant to oxidation. The invention is concerned with improvements in the treatment of lubricating stocks to effect increase in oxidation stability and to produce oils of highly stable character adapted for turbine oils, lubricating oils for internal combustion engines and the like.

In accordance with the invention the oil is subjected to catalytic treatment in contact with a molybdenum oxide and alumina catalyst at critical conditions of temperature under which reactions occur which produce pronounced in- The catalyst promotes reactions in which the structures of the lubricating oil molecules which are relatively unstable to oxidation are modified to more stable structures, structures which inhibit the oxidation of lubricating oil, or to structures which may readily be removed from the oil by simple means such as distillation. The lubricating oil as a Whole is rendered more oxidation stable by the treatment. While it is difficult to determine the exact nature of the reactions occurring in the treatment it appears that in general there is some increase in both aromaticity and parafiinicity apparently at the expense of naphthenic rings.

The material which is found to exert the desired catalytic action comprises a composite of molybdenum oxide and alumina. The catalyst may be prepared in various ways. Thus molybdenum oxide may be deposited on alumina or bauxite or the molybdenum oxide and alumina may be precipitated from aqueous solutions. The proportion of molybdenum oxide Will ordinarily constitute about 515% by weight of the compo sition.

In accordance with the invention the lubrieating oil is contacted with the molybdenum oxide and alumina catalyst in pulverulent or comminuted form at temperatures within a range of about 650-750" F., the maximum oxidation stability improvement being ordinarilyeffected at temperatures approximating ZOO-725 F.

Under these conditions of treatment there is a certain amount of conversion into lower boiling oils and the production of a relatively small quantity of gas but there is practically no conversion into gasoline. In practicing the invention the lower boiling or lower viscosity oil that have been produced in the reaction are distilled off, advantageously by vacuum distillation, so as to produce a product of desired viscosity. By means of the process, lubricatingoils having oxidation stabilities adapted for high grade turbine oils may be produced with yields approximating 80% and higher of product of the same viscosity as the starting material.

The activity of the catalyst in effecting the increase in oxidation stability begins at temperatures approximating 650 F. Thus at temperatures of 600 F. and 630 F. there is practically no improvement in oxidation stability but at temperatures around 650 F. definite activity of the catalyst is found to exist. Thus for example, a lubricating oil having a test life of hours by the A. S. T. M. oxidation test for turbine oils was treated at 650 F. with 10% by weight of the molybdenum oxide and alumina catalyst and the test life was raised to 2'70 with a yield of 90.5% of product having the same viscosity as that of the starting material, The maximum improvement occurs at temperatures approximating 700- 725 F. As the temperature is raised above 750' F. the yield drops on rapidly and moreover the indications are that at these higher temperatures the increase in oxidation stability is reduced. Space velocities of the order of 0.5 or 1 or 2 have been found adequate to accomplish the desired increase in oxidation stability,

The invention is directed to the treatment of refined stocks which have been given such prior treatments as treatment with sulfuric acid and solvent refining. It is critical that the catalytic treatment herein disclosed be given to the oil subsequently to the acid treating or solvent refining because the latter treatments tend to greatly reduce the oxidation stability imparted to the oil by the catalytic treatment. Thus in practicing the invention for the production of very highly refined lubricating oil the raw lubricating stock is first given such acid and solvent treatment as may be required and is then given the catalytic treatment forincreasing the oxidation stability. The catalytically treated oil may, however, be subjected to filtration through clay or fullers earth at moderate temperatures for improvement in color Without impairing the oxidation stability.

In certain typical examples, the invention was applied to the treatment of a lubricating distillate from a Gulf Coast naphthene base crude. The distillate from the crude stills was rerun with caustic soda in vacuum distillation, a 500 pale oil stock being taken as one of the fractions. The pale oil distillate was solvent refined with liquid sulfur dioxide and then treated with sulfuric acid shows the results which were obtained.

Temperature 700 F. 7 725 F. 750 F.

A. S. T. M. Oxidation Test for Turbine Oils: I V

Method D18827T hrs. 960 960. 770 Method D663-44T hrs.. over 1,900 over 1,900 "1, 056 Yield "per cent.. 83. 5 77 73 'Ifhe yields are expressed as the net yields of products of the same viscosity jas that "of the starting 'material. Th fi ures under 700 Rexpress the avera'geresul't's of three runs. I

In the runs'given in the tableth'e oil undergoing treatment with the catalyst an initial pressure o f 100 p. s. ;i. g. of hydrogen. It appears to be conducive to superior results to provide an atmosphere of hydrogen during the treatment but it is not necessary to do so since the increase in oxidation 't e sit liiec'an'beobtained in the treatmht with the Catalyst Without "the use of hydrogen. I I V I Although 'a preferred embodiment or the inv'ention has been describedherein, it will 'be understood that various changes arid "r'rio'dific'ations may be made therein, while securing toe.

greater or less extent some or all of the benefits of the invention, without departing from the spirit and scope thereof.

I claim:

1. In the manufacture of lubricating oil of superior oxidation stability the process that comprises first subjecting the raw lubricating stock obtained from crude petroleum to refining treatment involving acid treating and solvent refining and then contacting the refined lubricating oil with a composite of molybdenum oxide and alumina at ateniperature within the range of 6 50-750;F. to thereby efiect reactions causing increased oxidation stability.

2. In the manufacture of lubricating oil of superior oxidation stability the process that comprises first subjecting the raw lubricating stock obtained from crude petroleum to refining treatment involving acid treating and solvent refining and then contacting the refined lubrioating oil with a composite or molybdenum oxide and alumina at temperatures approximating 7009725" F. to thereby e'fiect reactions causing increased oxidation'stabil'ity.

FRED C. TOETTCHER.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,339,717 Oberfell Jan. 18, 1944 2,365,751 Drennan Dec. 26, 1944 2,392,248 Layng etal, 'Jan. 1,1946 

